/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} root
 * @return {number[]}
 */
var rightSideView = function(root) {
    const res=[],queue=[root]
       if(!root)return res
       while(queue.length){
           let len=queue.length,temp=[]
           for(let i=1;i<=len;i++){
               let node=queue.shift()
               temp.push(node.val)
               node.left&&queue.push(node.left)
               node.right&&queue.push(node.right)
           }
           res.push(temp[temp.length-1])
       }
          return res
   };